Copolymerization of alkylene sufides



United States Patent O 3,317,920 COPOLYMERIZATION F ALKYLENE SULFIDESManfred Sander, Frankfurt am Main, Germany, assignor, by mesneassignments, to Mobil Oil Corporation, a

3,317,920 Patented May 2, 1967 ing less than 30% ethylene sulfide thatare rubber-like and, as compared to poly (propylene sulfide), have ahigher tensile strength and lower elongation. In general, the copolymersembodied herein exhibit a decreased and less sharp melting temperatureas the proportion of propylwrpomfion of New York 5 ene sulfidezethylenesulfide is increased. Variations in N0 Drawing Filed 13, 1963, g Nun331,394 physical properties of copolymers embodied herein, as a 2 Claims1, g 0 79 function of the ratio of the copolymerizable components,

is shown by the data in the following tabulation in which The presentinvention relates to novel copolymers of the designation ES stands forethylene sulfide and PrS for lower molecular weight alkylene sulfidesand, more parpropylene sulfide.

WeightRatio of Reactants Solubility in- Melting Sulfur Temperature, 7Content E S PrS C. Tetrahydro- B enz ene Chloroform D ioxane D imethyl D1' methyl furan Iormamide sulfoxide 100 210 160 o 52. 3 90 10 188-193145 0. 150 C 51. 9 75 165-175 130 C. 130 0 50. 4 50 50 115-135 70 o. 1150 48.1 25 75 125 C 45. 4 1o 90 135 0. 44. 7

*Elastomeric soft.

ticularly, to such copolymers of ethylene sulfide and That thecompositions for which data are set forth in propylene lfid theforegoing tabulation are copolymers, rather than a High molecular weightpoly (ethylene sulfide) in the mixture of poly (ethylene sulfide) andpoly (propylene form of a highly crystalline solid having a relativelyhigh sulfide), is evidenced by the fact that polymer fractions, meltingpoint (e.g., about 210 C.) can, for example, be obtained by partialdissolution or partial precipitation from prepared by polymerizingethylene sulfide in presence of solutions, show sulfur contents similarto the unfractionan alkali metal. Such polymers are insoluble in manyated polymers; and, in view of the extreme differences in organicsolvents up to temperatures of approximately 150 solubilitycharacteristics of poly (ethylene sulfide) and C. On the other hand,high molecular weight poly (propoly (propylene sulfide), mixturesthereof rather than pylene sulfides) are soft, elastomeric substancesthat are copolymers would permit a substantially quantitativesepasolub-le in many organic solvents and, therefore, possess rationupon solvent extraction. substantially different characteristics thanpoly (ethylene The copolymerization reaction embodied herein can besulfide). Other poly (alkylene sulfides), prepared from carried out bycationic or anionic polymerization using alkylene sulfides of highermolecular weight than propylan alkali metal in the form of the metalitself or a highly ene sulfide, as for example, 'butylene sulfide,generally pos- 40 basic compound thereof. Although the copolymerizationsess properties similar to poly (propylene sulfide). Thus, reaction canbe carried out with relatively larger amounts for particularapplications, it is desirable to haveavail of the copolymerizationinitiator (i.e., alkali metal), it able copolymers of sulfides (such asthose of ethylene usually is carried out with an amount of alkali metalsulfide and propylene sulfide) that, as compared to the that does notexceed about one percent, based on the individual polymers of saidcomponents, possess substanweight of the reactants to be copolymerized,and preftially the desired properties of each of said individual erablywith an alkali metal concentration of from about pglymers, 1.0 to about0.01%, or less. Furthermore, the copolym- In accordance with thisinvention, it has been discovered erization reaction is preferablycarried out in presence that copolymers, rather than mixtures of poly(alkylene of an inert liquid reaction medium, preferably a polarsulfides), can be prepared by polymerizing a mixture of solvent, andexamples of which include ketones such as lower molecular weightalkylene sulfides containing from acetone and methylethyl ketone, andother organic comtwo to four carbon atoms, particularly ethylene sulfidepounds such as dimethyl formamide, dimethyl sulfoxide, and propylenesulfide, in presence of an alkali metal. and others.

Although the present invention embodies copolymers Desirably, thecopolymerization reaction is carried out prepared by copolymerizing themixture of alkylene sulwith use of the alkali metal catalyst in finelydivided or fides in any proportion, in preferred embodiment, itredispersed form as, for example, as powdered metal, granlates tocopolymers prepared by copolymerizing such a ular metal, metal chips,metallic films on carriers, etc. mixture containing from about 10 to 90%of one of the The reaction can also be carried out with the catalystmonomeric alkylene sulfides. metal dissolved in a suitable solvent and,for example, a

By the process embodied herein, and illustrated by cosolution of sodiumin liquid ammonia. Examples of polymerization of ethylene sulfide andpropylene sulfide, alkali metals for use in practice of this inventioninclude there can, for example, be prepared copolymers containsodium,potassium, rubidium and cesium with sodium ing more than 50% ethylenesulfide that are solids and, being a preferred embodiment. as comparedto poly (ethylene sulfide), are of lower melt- 6 The desiredcopolymerization reaction can be carried ing point, more elastic, le'sscrystalline, and of higher impact strength. Copolymers can also beprepared, containout at room temperature or at temperatures below orabove room temperature (about 20 C.). If elevated temperatures areemployed, it is advisable to run the reaction in a sealed vesselinvolving techniques conventional with other polymerization reactionswithin the skill of the art.

In order to further describe the invention, the following are set forthfor purposes of illustration and not limitation:

Example 1 A solution of 5 grams of ethylene sulfide and 5 gramspropylene sulfide in 100 ml. acetone was treated with 18 mg. sodium (inthe form of a dispersion in toluene).

Afterabout 2 minutes polymerization started in an exothermic' reactionresulting in the granular precipitation of a copolymer insoluble inacetone. After 1 hour water and some hydrochloric acid were added, thenthe polymer was filtered, washed with 10 percent hot hydrochloric acidand subsequently with large quantities of hot Water I tent of thesubstance amounted to 48.1 percent.

2 grams of the substance was boiled for minutes with 50 ml. chloroformwhereby 1.1 grams dissolved. The solution was evaporated to a residuethat contained 47.8 percent sulfur; the undissolved substance contained48.0 percent sulfur.

Example 2 A solution of 2.5 grams ethylene sulfide and 7.5 gramspropylene sulfide in 50 ml. acetone was treated with 17 mg. sodium (inthe form of a 10% dispersion in toluene) and stirred for 1 hour.Subsequently the mixture was refiuxed for 30 minutes. After distillingoff the acetone, the residue was dissolved in benzene and the benzenesolution washed with dilute hydrohloric acid and water and finallyevaporated. 8.7 grams of a soft, elastomeric solid was obtained whichwas soluble in chloroform, dioxane and dimethyl formamide. The substancedissolved in dimethyl sulfoxide above 125 C. The reduced viscosity of a0.5 percent solution in dimethyl sulfoxide at 175 C. was 48 cm. g.- 45.4percent sulfur.

Example 3 ,0

As described in Example 2, 1 gram ethylene sulfide and 9 grams propylenesulfide were polymerized in 50 m1. acetone in the presence of 16 mg.sodium. 8.7 grams of a elastomeric polymer containing 44.7 percentsulfur was obtained. The reduced viscosity in dimethyl sulfoxide at 175C. amounted to 19 cm. -g.

Example 4 As described in Example 1, 8.25 grams ethylene sulfide and2.75 grams propylene sulfide were polymerized in 100 ml. acetone in thepresence of 19 mg. sodium. 10.3 grams of a colorless, fine powder wasobtained as polymer, which melted between 165 and 175 C. The substancescontained 50.4 percent sulfur. The reduced viscosity in dimethylsulfoxide at 175 C. was 25 cm. g.- The substance was insoluble inbenzene, tetrahydrofuran,

The substance contained chloroform and dioxane, and soluble in boilingdimethyl. formamide and, above C. in dimethyl sulfoxide.

Example 5 As described in Example 1, 9 grams ethylene sulfide: and 1gram propylene sulfide were polymerized to 100 ml. acetone in thepresence of 19 mg. sodium. 8.8 grams of a colorless,- fine powder wasobtained, which melted between 188 and 193 C. The substance contained51.9 percent sulfur. The reduced viscosity of a 0.5 percent solution indimethyl sulfoxide at C. amounted to 22 cm. g.

The copolymers embodied herein can be processed to desired shapes bymethods generally used for thermolastic materials, for example, bycompression molding,

extrusion molding, or injection molding. Fillers, pigments, coloringmatter or other additives can be admixed with the polymer. Processing ofthe copolymeric products embodied herein in the form of melts arepreferred for formation of shaped structures such as films or fiberswhich, depending on the relative proportions of the monomeric sulfidesemployed for the copolymerization, possess desired properties such asresistance to chemical attack and, especially, against attack by acidssuch as hydrochloric acid and alkaline solutions.

Although the present'invention has been described with preferredembodiments, it is to be understood that modifications and variationsmay be resorted to, without departing from the spirit and scope of thisinvention, as those skilled in the art will readily understand. Suchvariations and modifications are considered to be within the purview andscope of the appended claims.

Whatis claimed is:

1. A process for preparing copolymers of lower molecular weightalkylenesulfides which comprises. copolymerizing a mixtureof alkylene sulfidescontaining from two to four carbon atoms in an inert polarorganic liquidreaction medium andin the presence of an alkali metal.

2. A process according to claim 1 in which said alkali metal is sodium.

References Cited by the Examiner UNITED STATES PATENTS 2,183,860 12/1939Colt-of 260'79 2,185,660 1/1940 Coltof et al. 26079 3,071,593 1/1963Warner 26079 3,222,324"12/1965 'Brodoway 26079 3,222,325. 12/1965Brodoway 260327 3,222,326 12/1965 Brodoway 260-327 ,3 OTHER REFERENCESChemical Society Journal, vol. 56, 1934, pages 2177 to DONAL]? E.CZA-JA, Primary Examiner.

LEON I. BERCOVITZ, M. I. MARQUIS,

1 'Assistant Examiners.

1. A PROCESS FOR PREPARING COPOLYMERS OF LOWER MOLECULAR WEIGHT ALKYLENESULFIDES WHICH COMPRISES COPOLYMERIZING A MIXTURE OF ALKYLENE SULFIDESCONTAINING FROM TWO TO FOUR CARBON ATOMS IN AN INERT POLAR ORGANICLIQUID REACTION MEDIUM AND IN THE PRSENCE OF AN ALKALI METAL.